Liquid applicators such as paint rollers have come into very widespread use due to their ability to apply coatings, usually paint, economically and quickly. Nearly every paint roller in commercial use today consists of a frame which terminates at one end in a handle and, at the other end in a cage and cover support rod, a cage received on the support rod, and a roller cover received on the cage. The term "roller" or "roller assembly" when used herein will be used to refer to the just described components, namely (1) a frame having a handle and a support rod, (2) a cage and (3) a roller cover.
The roller and the cage are almost always separable. This is so in order that the cover can be cleaned, or stored, possibly under water until the next use, or thrown away to make room for another cover. Thus, the roller and the cage, at least, are assembleable and disassembleable components which form a sub-assembly of the roller assembly.
The operating requirements of the assembleable/disassembleable cage and roller subassembly of the roller are well defined and, to some extent, at cross purposes. Thus the cage must securely hold the cover during use so that the cover does not "walk off" the cage during use with obviously disastrous consequences, particularly if the cover has just been fully loaded with paint. However, at the same time, the securement between the cover and the cage must not be so tight that separating the roller from the cage at the end of a session's use by the operator (i.e.: for cleaning, storage or discard) is difficult. In addition, nearly all covers consist of an inner tube having a nominally constant bore, which receives the cage, and an outer surface to which the fabric receives and discharges paint. In many cases, due no doubt to the highly competitive nature of this product and thus the inability to provide highly-engineered components which always fit together perfectly, there is a degree of interference between the cover and the cage. The internal diameter of the bore may not be constant for example and thus the cage may have varying degrees of contact with the bore in those areas in which the inside diameter of the bore goes oversize. By the same token the outside diameter of the cage structure may vary due to manufacturing variances, or damage while in use, and hence sections of the cage may make no contact, or only imperfect contact, with the cover so that the convenient removal of the cover from the cage cannot be achieved.
Further, many cages are structurally complex and hence both unduly expensive and unduly susceptible to improper functioning traceable to the complexity of the construction. For example, one widely sold roller includes a first cage element which is assembled to the free end of the support rod, the cage element including a plurality of radial fins which extend inwardly toward the center of the cover only a short distance from the free end, a second cage element which is assembled to the handle end of the cover and also includes a plurality of similar radial fins which extend inwardly from the handle only a short distance, and a third element consisting of a spacer which is located between the two opposed ends of the first and second elements, the only purpose of the spacer being to maintain the first and second elements in fixed, spaced relationship one to the other. The second element which is closest to the handle is often formed with a flange so as to preclude the cover from "walking" toward the handle. The first element cannot have such a flange or there would be no way to assemble the cover to the cage without running the risk of losing cage components, or improperly reassembling the cage. Thus, this common cage construction includes three separate and differently contoured components and substantial assembly costs are incurred in assembling them to the cover both in terms of equipment needed and time required. In addition, should the three cage components come loose from the cover after the sub-assembly of the cover and the cage has been removed from the support rod, the reassembly of the cage components to the roller may be beyond the mechanical skill of many consumers-users. First, for example, should the spacer be lost and the cover with the two end elements reassembled to the support rod without it, subsequent failure is likely to occur because there is nothing to maintain the end elements in proper spaced relationship. Second, for example, the outer core element may creep inwardly during use causing paint to build up in the space at the end of the tube which has been vacated by the first cage element. Should the user carelessly or intentionally permit the deposited paint to harden prior to the next use, the removal of the cover, as when it is worn, or to install a different cover with a different fabric nap to do a different painting task, may be nearly impossible for the average consumer-user.
A further shortcoming of most commercially available rollers is the high molding costs and the high assembly costs associated with fitting the cage and cover to the support rod using the current attachment methods such as crimps, washers, push nuts and other multi-piece attachment mechanism.